Method for remotely monitoring the long term deep body temperature in female mammals

ABSTRACT

This invention relates to a novel method for remotely detecting and monitoring on a long term basis the deep body temperature of a mammalian female which comprises the steps of attaching a temperature-sensing probe capable of remote interrogation to an expandable anchor, implanting the probe with the anchor attached thereto in collapsed condition within the vaginal canal, expanding the anchor to maintain the probe in place despite the animal&#39;s muscular efforts to expel same, interrogating the probe from a remote location on a daily basis at approximately the same time each day for a period not less than one complete estrous cycle, and noting any abrupt change in temperature within each cycle as an indication of physiological stress.

Livestock breeders, especially cattlemen, find that one of their majorconcerns is that of being able to maximize the conception rate of theirfemales. A conception percentage of 80% or above is considered good. Inthe dairy industry where husbandry is practiced more intensively than inordinary beef production, .[.diarymen.]. .Iadd.dairymen.Iaddend.consider that a poor conception rate is one of their mostsignificant management as well as economic problems. The root of theproblem is basically the failure to reliably detect estrus. This isespecially significant in the dairy industry because dairy cattle are,for the most part, hand bred and the herd manager or operator must knowwhen to introduce the cow to a bull or else inseminate her artificially.As valuable a tool as artificial insemination is to the dairy industryand others, it is being used far less than it should be because of thedifficulties associated with detecting estrus, some of which at leastcan be solved by a bull in conjunction with an assortment ofcommercially available detection aids which provide visual evidence ofwhen the bull has mounted the cow.

A cow that has not become pregnant within 80 days after calving coststhe dairyman in excess of two dollars per day in lost income and actualout of pocket expenses. The cow who exhibits abnormal reproductivity, onthe other hand, can easily go undetected for even a much longer periodof time.

Apart from using the bull, stallion or boar as a means in and of himselfor in conjunction with some artificial aid to detect ovulation, muchattention has been given to the detection of abnormal body temperatures,even in humans. For the most part, the detection of temperature changesin bovines and equines has, up until recently, been reliant uponstandard temperature probes such as ordinary thermometers that weretemporarily inserted by hand into the rectum or vulva for the briefinterval required to get a reading and then removed. Obviously, such atechnique requires confinement of the animal and a great deal of timeand effort on the part of some human being. This labor-intensive effortis completely impractical for use over the extended period of timerequired to develop a temperature history for the animal adequate to useas a basis for noting any anomalous state of affairs.

Early illness detection presents yet another problem because,ordinarily, the animal does not have her temperature checked until overtsigns of physical illness have become apparent to the observer. This isoften hours, if not days, after the onset of the illness thusnecessitating a longer recovery, greater expense and other undesirableconsequences. In the dairy herd, rapid illness detection becomesespecially significant due to the decreased milk output, possible drugcontamination of the milk, reduction in feed conversion efficiency, etc.

It has been recognized for quite a long time that various significantphysiological changes in female mammals, including the human species,could be detected through change in deep body temperature before otherexternal manifestations provided any clue to what was taking place.Ovulation in human females can, for example, be detected in some womenby a careful monitoring of their body temperature and such a procedureis in rather widespread use as a birth control system. While theso-called "basal body temperature" (BBT) has been known for a long timeto bear an important correlation to the menstrual cycle of a humanfemale, it has also been found that the usual oral and rectal methods ofmeasuring body temperatures lack the precision necessary to detect therather minute incremental changes that signify the onset of ovulation.In an effort to solve this problem and measure the BBT in the humanfemale with greater precision, Dr. John H. Mattox et al. implantedaccurate temperature sensing instruments intravaginally in a number ofwomen. These instruments telemetered the BBT to remote data collectionstations which monitored it and compared the results over severalmenstrual cycles with similar BBT's taken orally. The results of thisstudy were published in Volume 27, No. 9 dated September 1976 of thereports of the American Fertility Society following presentation of apaper on the subject in October 1975 at the Annual Meeting of thePacific Coast Fertility Society.

While the foregoing study clearly demonstrated the practicality oftelemetering deep body temperature data to a remote data collectionstation from a site within the vaginal canal of a human female, it alsoclearly showed how complex such a system is and how much cooperation onthe part of the participants was necessary in order to provide theinvestigators with reliable data. Also, not one of the women whoparticipated in the study left the temperature probe implanted more thana few hours out of each day and, while the investigators felt that the"cumbersome and complex" system could probably be simplified, theyagreed that their study using an intravaginal probe did little more thanestablish the worth of the conventional oral temperature method as ameans for detecting ovulation. Clearly, a system such as that employedby Dr. Mattox was unsuitable for livestock since the study demanded agreat deal of intelligent cooperation on the part of each participantwhich an animal is totally incapable of providing.

.[.Diarymen.]. .Iadd.Dairymen .Iaddend.have known for years that a cow'sbody temperature is capable of foretelling the onset of estrus as wellas conditions of poor health like, for example, mastitis and otherfever-inducing ailments. They also knew that a cow's temperature variedgreatly with ambient conditions and were by no means the same from oneanimal to the next even under identical conditions thus, while it hasbeen recognized that a long term temperature history of a particular cowrelated to the change in ambient conditions should be very helpful indetecting the small abnormalities in the temperature profile for a givenanimal that are needed for a reliable prediction of estrus or a febrileillness, no way was known in 1978 for obtaining such information asreported in Hoard's Dairyman by Armstrong and Wiersma; 123(13): 823,July 10, 1978. These authors reported attempts at measuring milktemperatures and analogous body temperatures predicated upon the latterbut the clear conclusion was reached that "It is apparent that the useof cow body or milk temperature for early detection of mastitis, estrusor illness has little value under Arizona conditions." This same articlealluded to a study in The Netherlands when monitoring the milktemperature in the claw-piece of the milker was effective in detectingestrus in 16 out of 19 cows based upon a 0.5° change; however, theseauthors seriously doubted whether deviations of this order of magnitudeand less would be effective under the conditions they were working underin Arizona and their conclusion was that they would not. Even beforeArmstrong and Wiersma were conducting their milk temperature experimentson dairy herds in Arizona, others had experienced much the same thing inconnection with different types of temperature measurements in dairycattle.

During roughly the same period in which Dr. Mattox and his associateswere making the deep body temperature study on the human female, otherswere attempting to use intracranial temperature measurements taken inthe ear canal of dairy cattle to provide better reproductive management.M. Lira et al. reported the results of their study at the annual meetingof the American Dairy Science Association held at Kansas StateUniversity in Manhatten, Kans. during June of 1975. As was the case withthe Mattox study on human females, the ear canal probes were insertedand removed on a daily basis rather than being implanted and left inplace over a prolonged period of time, say a complete estrous cycle orlonger. The readings that were taken were confined to the day of estrusand six days before and after. The data taken during this study revealedthat the temperature of the animal was elevated very slightly and wassignificantly different (P<0.01) on the day of estrus and that the earcanal measurement coincided closely with that taken rectally. One isforced to conclude that whether the body temperature is taken rectallyor intracranially, it must be taken quite accurately to detect a changein the order of a tenth of a degree. Common sense dictates that manyfactors, both external and internal, could be responsible for such aslight change and, for this reason, little reliance can be placed uponthe detection of a change of this order of magnitude.

Various investigators at Los Alamos Scientific Laboratory operatingunder a contract from the U.S. Department of Energy have conductedextensive tests over the past several years on the telemetering of bodytemperature data and other information from livestock carrying bothself-contained battery-operated transmitters and AC powered ones. Amongother publications, the Holm et al. Progress Report LA-7642-PR entitled"Electronic Identification" of May 1979 summarizing work done betweenOct. 1, 1977 and Sept. 30, 1978 provides one with a fairly comprehensivesummary of these activities which were, for the most part, focused uponwhat would be required in a cost-effective system that could beimplemented on a national basis to trace the movement of livestock,their physical condition, location, and other factors such as stress andestrus that would be of assistance to the industry in terms of herdmanagement, disease control, reproduction and the like. For presentpurposes, this research is significant in that it did provide long termassessment of the body temperature of animals using so-called "on board"telemetry equipment capable of being monitored at a remote site. So faras is reflected from the above report, the nearest approach to deep bodytemperature readings that were taken came from transponders implantedsurgically subdermally. While body temperatures were measuredintracranially within the ear canal as had been done in the past, thesereadings do not qualify as deep body temperature readings nor do thosetaken rectally. As such, there is no teaching of any long termmonitoring of deep body temperatures within a natural body cavity like,for instance, the vaginal canal of a female animal such as a cow, mareor sow.

Essentially, the foregoing publications reflect the state of the artwith respect to the detection and monitoring of deep body temperaturesin mammalian females for any purpose as well as for the specificpurposes of recognizing the onset of illness, estrus or other similarphysiological stress. Before proceeding with a description of the novelmethod for detecting the onset of estrus or febrile illness by means ofthe intravaginal measurement of deep body temperatures in femalemammalian livestock that constitutes the subject matter of the instantinvention it would, perhaps, be helpful to look briefly at why suchinformation is important to the commercial livestock industry, the dairyindustry and horse breeders, among others.

Take, for instance, the dairy industry which can be consideredrepresentative of similar situations existing in each of the others. Itcan be shown that losses due to poor reproduction alone accounted forlosses totalling over a half billion dollars some ten years ago and inthe present state of the argicultural industry, these losses are sure tobe much greater. These losses are broken down into three broad areas asfollows:

(1) Loss of production--milk and calves,

(2) Replacement costs, and

(3) Additional breeding costs (vet services and medication).

With respect to the first of these, as of ten years ago a fair consensustaken from recognized agricultural economists indicated losses to thedairyman of about 70 cents per day resulted for each day beyond theoptimal yearly calving interval that a cow did not conceive. Since theoptimal yearly calving interval is recognized to be twelve months andthe yearly average back in 1970 was 13.5 months, the nationwide loss tothe dairy industry in the United States which numbers some twelve and ahalf million cows represents a loss of just under $400,000 annually.

Add to the above the replacement cost factor nationally even back in1970 of a little less than $94,000,000. These losses were occasioned bythe fact that somewhere near 5% of the cows had to be slaughteredbecause of their failure to conceive within a reasonable time or at allcoupled with the difference of around $150.00 per animal that thedairyman had to absorb as the disparity between the salvage value of theanimal slaughtered and her replacement.

A similar analysis will reveal that in excess of $50,000,000 more isspent on the increased number of average services per unproductive cowthat are required in the attempt to successfully breed her and theunusually high vet bills required for such an animal. A significantreduction in these losses could be realized by a reliable earlydetection of estrus in these animals accompanied by promptly breedingthem for calving at the recommended twelve month time interval.Significant losses can also be demonstrated for both beef cattle andhogs. While the horse breeding industry has different economic problems;nevertheless, an early and reliable detection of estrus in the mare canprove to be of substantially financial advantage.

In addition to the significant economic losses occasioned by inefficientbreeding, infection and metabolic stress are equally costly problems.Looking again at the dairy industry for an idea of the magnitude ofthese problems, it can be shown that common dairy herd diseases likemastitis, ketosis and milk fever accounted a decade ago for losses wellin excess of a half billion dollars; yet, prospects are favorable forcutting these losses almost in half by merely detecting these diseasesin the sub or preclinical stage before they progress to the clinicalstage where they manifest themselves in a way that they can be detectedby the usual methods. Early detection of febrile illness holds goodpromise of prompt treatment and a favorable prognosis that shortens thephysical setback and restores the animal to full production before hermilk output is adversely affected, at least to the degree it would be ifthe disease were allowed to progress further.

For the most part, cows and sows are bred artificially, therefore, thebest natural means, namely the bull or boar, for detecting when thefemale is in heat are not available thus necessitating some other methodfor detecting estrus. This is not to say that accurate estrus detectionis not also worthwhile in natural breeding. Take for example, horseswhich are bred naturally. Stud fees are generally based upon thestallion having to service the mare three or four times to insure thatshe is pregnant. If, on the other hand, he had to stand only once foreach mare and could, therefore, service several, the stud fees could bereduced to a considerable degree. In the case of sows, they are known toexhibit no external signs of being in heat on occasion and, therefore,even the boar is no help under such circumstances.

Thus, while accurate body temperature measurements are known to providea reliable indication of both estrus and the onset of febrile illnessesin mammalian females, both human and animal, no one has yet developed asystem for reliably ascertaining this condition, especially with animalsunder practical herd management conditions. It has also been discoveredin accordance with the teaching of the instant invention that animalsdiffer in their body temperature patterns from humans and, therefore,absolute or "spot" readings cannot be relied upon in animals but ratheronly the change in temperature from one day to the next recorded atapproximately the same time each day and over an extended period oftime, preferably one that encompasses more than one estrous cycle.Moreover, small as the changes are, if accurately measured they arecapable of differentiating between the onset of an illness and estrus,the former generally being of greater magnitude than the latter whilethe latter is the shorter-lived of the two.

Temperature measuring instruments, even those sufficiently small to beimplanted, having the requisite accuracy present no problem as they arecommercially available in the marketplace as is the radio-telemetrysupport system capable of transferring the "onboard" temperature data toa remote receiving station. While the cost effectiveness and longevityof such a system may prevent its being used on a widespread basis inrange cattle for sometime yet as evidenced by the Los Alamos study,nevertheless, the potential saving to the dairyman, hog farmer and otherbreeder of farm animals as opposed to range stock can be verysignificant. The real challenge is not the equipment but rather themethod employed to accurately measure and monitor the body temperatureof the animal in such a way and at such a site that it will reliablyprovide the desired temperature data from which accurate predictions asto the state of health and/or ability of the animal to conceive can bemade. The Mattox study previously mentioned apparently demonstrated theinapplicability of the human intravaginal implantation method to femaleanimals since the system was so complex and cumbersome that even thesupposedly "intelligent" human species failed to produce the expectedresults. Intracranial implantations in the ear canal proved less thaneffective in addressing the accurate temperature readings necessary fora reliable prediction of estrus or state of ill health as did thenotoriously old rectal method. Even the surgical implantation of theradio telemetry equipment was fraught with serious deficiencies, not theleast of which is the implantation itself. Nevertheless, the indicationswere that only deep body temperature measurements were sufficiently freeof ambient climatic factors and other external influences to a pointwhere the necessary degree of accuracy was attainable under herdmanagement conditions. Also, as a practical matter, relatively long termimplants appeared to be necessary since the herd owner could ill affordthe labor cost of having to take the deep body temperature of eachindividual animal separately at least once a day and preferably at thesame time. Another unknown factor was, of course, the traumatic effectsuch a daily procedure might have on the animal which might manifestitself in a brief rise in body temperature thus providing a falseindication of estrus or the onset of some illness.

With these limitations in mind and knowing that neither the ear canal orthe rectum provided the answer, the best possibility seemed to be thevaginal canal despite the indications to the contrary experienced byMattox with his human subjects or, perhaps, intrauterine placement. Bothof these internal sites held promise of providing a true deep bodytemperature reading essentially unaffected by external conditions. Also,following insemination, there appeared to be no reason for removing thetemperature probe and associated radio telemetry apparatus until thetime came for the animal to give birth. Furthermore, by leaving theprobe in place from insemination to parturition, a long history ofestrous cycles would be available for each animal on an individual basisin case the response happened to vary from one animal to another,seasonally or for some other reason.

Accordingly, it was decided to implant the probes and associatedtelemetry equipment within the vagina of cows, mares and sows to see ifsufficiently accurate deep body temperatures could be remotely sensed toprovide the investigator with a reliable indication of just when estrusor some other physiological change manifesting itself in a rise orlowering of body temperature took place. Unfortunately, while the theorywas sound, the early intravaginal experiment failed for the simplereason that the animal quickly expelled the probe through muscularaction, perhaps involuntary but nevertheless effective to rid her bodyof the foreign object.

Notwithstanding the foregoing setbacks, it has now been discovered inaccordance with the teaching of the instant invention that long term andremotely readable deep body temperature readings that are accurate andvirtually unaffected by external conditions can, in fact, be takenintravaginally by the simple yet unobvious, expedient of attaching thetemperature probe to an expandable anchor, inserting the probe andanchor deeply within the vaginal canal with the anchor in collapsedcondition, permitting the anchor to expand to hold the probe in placedespite the muscular actions of the animal in an effort to expel same,interrogating the sensor daily from a remote station at approximatelythe same time each day for a period of not less than one full estrouscycle, and noting any change in the deep body temperature of the animalduring the aforesaid cycle as a means for detecting estrus or the onsetof febrile illness.

It is, therefore, the principal object of the present invention toprovide a novel and improved method for the remote detection ofphysiological changes taking place in female mammals.

A second objective is the provision of a method of the typeaorementioned wherein surgical invasion of the animal is unnecessary.

Another object of the within described invention is to provide a meansfor monitoring the body temperature of a female mammal on a long termbasis such that the data taken is virtually unaffected by externalconditions, stress or other outside factors.

Still another objective is to provide a method of the characterdescribed which is sufficiently accurate to enable one to reliablydetect both the onset of febrile illness and estrus while, at the sametime, permitting the observer to differentiate therebetween.

An additional object is to provide a long term remote temperaturesensing method particularly well suited to female farm animals of thebovine, equine and porcine species which is cost-effective and practicalunder herd management conditions.

Further objects are to provide a body temperature monitoring method formammalian females which is simple, efficient, dependable safe,relatively inexpensive, long-lasting and one that is easily carried outby unskilled personnel.

Other objects will be in part apparent and in part pointed outspecifically in connection with the description of the drawings thatfollows, and in which:

FIG. 1 is a diagram showing placement of the probe and the anchortherefore in the vagina of the animal; and,

FIGS. 2-7 are charts detailing the long term intravaginal temperatureresponse of various species of female mammals.

Referring initially to FIG. 1, the temperature sensing probe 10 used inthe instant method is conventional and it consists of a battery poweredtransmitter containing a temperature-sensing thermistor which sends outa pulsed signal, the rapidity of which corresponds to the temperature ofthe transmitter and also the deep body temperature of the animal whenimplanted in her vaginal canal 12. The transmitter 10 has been shownwithout detail but approximately its actual size in relation to a growncow's vagina 12. The resulting signal is sensed at a remote locationoutside the animal's body. The location of the receiver 14 is optionaldepending upon its sensitivity and the strength of the signal generated,some receivers being responsive to signals originating miles away fromthe transmitter. The selection of signal strength and receiversensitivity is a matter of choice well within the skill of the art andwill depend to a considerable degree upon several extraneous factorssuch as the size of the herd, the ability of the equipment todifferentiate among the several animals, the degree of confinement ofthe herd, if any, and other similar parameters.

The signal that is received is recorded and analyzed during apreselected time period, say five minutes, at the same or approximatelythe same time each day. In bovine animals, for instance, it is awell-known fact that the lowest body temperatures of the day occur earlyin the morning between approximately 5:00 and 7:00 a.m. The baselineagainst which the spikes are most evident is likely to be establishedduring such a time period; therefore, for cattle at least, themeasurements are preferably made during this minimum baselinetemperature interval.

For small confined herds, tunable receivers are unnecessary provided thetransmitted signal is relatively weak. In such a circumstance, thereceiver is placed in reasonably close proximity to the particulartransmitter whose temperature signal is to be decoded so as to screenout other extraneous signals. On the other hand, care should be taken tonot excite the animal thus inducing a false spike which is often thecase with transponders inserted into a body cavity and removed aftersuch reading in the manner of Mattox and others.

The battery powered radio transmitter 10 containing thetemperature-sensitive thermistor is implanted at the mouth of the cervix16 where, for purposes of making dependable and accurate predictions, itmust stay for at least one complete estrous cycle and preferably fiftydays or longer. Because of the stress-induced fluctuations intemperature, handling of the animal should be minimized; however, a 50day test performed at the proper time will allow the animal to settledown while at the same time provide good baseline temperature dataagainst which the spikes become easy to detect as will appear presently.Notwithstanding the long term implantation of the radio transmitter, itremains readily accessible to serve, repair and change batteries, allwithout having to resort to surgical invasion of the animal or requirethe services of a D.V.M.

The act of implantation is a simple one using standard techniques andinstruments like, for instance, a trochar tube and pushrod or plungerinside the latter. The problems do not arise in connection withplacement of the probe but rather with how to keep it in place. Themuscle contractions and relaxations of the vaginal walls are such thatthey quickly eject any foreign object like the probe. The answer came inthe form of an expandable anchoring device which is introduced into thevagina in collapsed form and then expanded to provide a multi-fingeredelement which would yield under the influence of the contracting vaginalmuscles thus preventing them from getting a sufficient hold to ejecteither the anchor or the transmitter attached thereto back out throughthe vulva. One spider like form of anchor which has been used with goodresults is shown in FIG. 1 and identified by reference numeral 18. Adevice having characteristics very much like the anchor shown, but for adifferent purpose, forms the subject matter of one or more of thefollowing U.S. Pat. Nos. 3,811,423; 3,811,443; 3,811,424; and 4,091,807.

Once the probe is in place as shown, the herd manager or otherinvestigator can begin gathering data for the purpose of ascertainingwhen the animal is in condition to conceive or, alternatively, is notovulating and cannot be impregnated. This same data will be effective toindicate the onset of a febrile illness well before any overt clinicalsigns become apparent. The results of actual deep body temperaturemeasurements in three species of female livestock mammals form thesubject matter of the graphs appearing herein as FIGS. 2-7, inclusive,to which detailed reference will soon be made; however, before doing so,it would seem appropriate to digress briefly and explain a bit moreabout when the probe should be implanted and why it should be kept inplace for an extended period of time.

Cows and other female animals are known to have cyclic variations inbasal body temperature which cycle bears a relationship to the estrouscycle. This cycle was discovered to differ a great deal from that of thehuman female. One major difference is the fact that women experience anear constant temperature pattern from period-to-period, whereas, cattleand other animals do not. The fact of the matter is that farm animalsexhibit a changing temperature pattern which seems to depend to somedegree at least upon the climate and the season. For instance, it can bedemonstrated that the normal body temperature baseline takes on anascending pattern during prolonged periods of cold weather and adescending one when it is warm. It is essential, therefore, that afairly long term history of not less than a complete estrous cycle andpreferably even longer, say 50 days, be kept and used as the basis fordetecting any significant changes such as those that signal ovulation orthe onset of febrile illness.

In the human female, despite the constant temperature pattern betweenperiods, Mattox found he could not .[.realiably.]..Iadd.reliably.Iaddend. detect ovulation based upon deviations from thispattern even though he was using highly motivated, intelligent andcooperative women. Nonetheless, and contrary to what one might expect,readily detectable temperature spikes signalling ovulation do occur infarm animals. Even though the baseline temperature varies seasonally andwith environmental conditions, it has been discovered in accordance withthe teaching of the instant invention that ovulation can be reliablyascertained provided a sufficient temperature history leading up to theanomaly or spike is available. The proof is, of course, that animalsbred on such a spike get pregnant while those bred at other times donot.

More specifically, the estrous cycle is such that a pronounced spike inthe order of 0.8° C. is noted on the day of estrus in a cow, forexample, while an equally prominant dip in temperature takes place onthe preceding day and again on the following day when ovulation occurs.This cyclic pattern happens in cows with so-called "silent heats" aswell as those with normal heat periods. This 0.8° spike lasts for oneday only and it is detected by measuring it against her average bodytemperature over the preceding ten day period or thereabouts.

In a dairy herd, for example, a cow's greatest milk is produced providedshe is inseminated within 90 days after parturition; yet, statisticsshow that about one-third of all dairy cows miss this target for thereason that over 40% of these cows never have a heat period recordedwithin the first sixty days after they have calved and an additional 12%or so go over ninety days. Even after the first heat period followingparturition is recorded, about one in every six thereafter is missed.For these reasons alone, it is of utmost importance if cost-effectivedairy herd management is to be achieved, that each of these heatperiods, and preferably the first, is reliably detected.

Turning the attention next to the graph of FIG. 2, wherein Mare I showedfour spikes (A, B, C and D) that surpassed a threshold line (spikeindicates about 3/4° C. above mean). These spikes are spaced at regularintervals that coincide with the expected time between ovulations. Also,spikes A, B and D were associated with estrus. The mare was not teasedduring the period of spike C, so the estrus status is not known. Eachdata point (dot) represents a once-daily reading taken at approximately7:30 a.m. between May 9 and Aug. 12, 1979. The ordinate scale is inradio counts per 5 minute period.

Mare II charted in FIG. 3 showed four substantial temperture spikes(magnitude about 3/4° C. above mean) which extend above the thresholdline. Spikes B and D occurred at the last day of the estrous period. Themare was not teased during the period of spike A, so her receptivity isnot known. The spike C occurred during mid-estrous and, curiously, nospike appeared during the subsequent estrous period. Each data point(dot) represents a once-daily reading taken at approximately 7:30 a.m.between June 1st and Aug. 10, 1979. The left side scale is in radiocounts per 5 minute period.

The intravaginal temperature graph of FIG. 4 was taken of a sow insteadof a mare. The sow exhibited two heat periods of 2 days duration whichis characteristic of sows. There were temperature spikes (A and C)towards the end of each heat period. The sow was accidentally bred onthe second day after spike C and became pregnant. Spikes A and C werenineteen days apart which matches exactly the normal ovulation intervalfor sows. Spike B was quite high and indicates a fever of short durationwhich might well have been due to a mold infection such as a virus mightcause.

Directing the attention next to FIG. 5, heifer 1474 initiallyexperienced three normal heat periods and there were temperature spikes(A and B) recorded as shown. The transmitter was not implanted in theheifer during the period marked xxx. Spike C was not accompanied bystanding heat, however, the interval was normal from the previous spikeand the heifer was bred. It is believed that she became pregnant andthen miscarried because she came in heat 28 days later with a spikeoccurring the subsequent morning. The 29 day interval was too long fornormalcy. Eventually, the heifer was bred again during a heat and spikeepisode and she became pregnant.

FIG. 6 to which reference will next be made details the temperaturepattern of yet another heifer. Heifer 1494 presented spikes A, B and Cduring her test period. She was just reaching puberty when brought intothe experiment. She only expressed heat once and that was accompanied byspike B; nevertheless, she did have normal intervals .[.beteeen.]..Iadd.between .Iaddend.the three significant spikes. Following spike Cshe did not show any mating behavior or spikes during a period of veryhot weather. Eventually, she did come in heat and had a smaller spike.She was bred and became pregnant.

Finally, with reference to FIG. 7, a cow 690 was selected because of herinfertility as a subject for examination of spike conditions duringknown reproductive insufficiency. There were two very high spikeswithout associated heat. She had a questionable heat once and a definitestanding heat towards the end of the observation period. The cow wasbred at spike B and did not become pregnant. Apparently, the cow isphysiologically out of phase and there was no normal periodicity in herrecord at all. This example clearly illustrates the value of theremotely-sensed temperature method of the present invention in detectingacyclicity and probable ovulation failure.

On the whole, the foregoing charts clearly reflect the day-to-dayphysiological conditions of the subjects. When her temperature readingis noticeably greater than her previous ten day average and exceeds allprevious highs during that time interval, the probability is that she ispreparing to ovulate and she should be bred on either the day of the.[.estrus.]. .Iadd.estrous .Iaddend.spike or early the next day. In thespecific case of cows, if the foregoing temperature spike falls on a21±5 day interval from the preceding spike, the cow is very probablyovulating; however, if the spike is out of phase with the normal estrouscycle as above noted and has a magnitude somewhere around three timesthe magnitude of previous spikes, the animal is very probably feverishand such a spike signals the onset of some febrile illness rather thanestrus and at a time well in advance of when any clinically recognizablesymptoms appear. The random occurrence of such spikes their magnitudeand duration (more than one day) allow the observer to readilydifferentiate between the fever spike and the estrus spike. It is alsosignificant to note that the failure to record a spike is equallyinformative because it signals the absence of ovulation which is everybit as important to know as when the animal is experiencing normalovulation (see FIG. 7).

The foregoing examples clearly demonstrate that, while the temperaturecycles of various species of female farm animals have long beenrecognized as effective indicators of estrus, until now there has neverbeen a reliable, practical and effective method for determining theanimal's temperature, deep body or otherwise, on a daily basis underherd management conditions. The instant method permits the long termmonitoring of the deep body temperature of a female mammal withouthaving to handle over and over again. The subject is natural at alltimes and need not be agitated as is the case with present deep bodytemperature measurement methods where the thermometer or other types oftemperature measurement probe is repeatedly inserted and removed fromher rectum or vulva every single day. The animal is not harmed in anyway or otherwise traumatized yet she is constantly providing theobserver with much needed information on her physical condition which isotherwise essentially unattainable under field conditions.

Summarizing, the instant method solves three heretofore unsolvedproblems, namely: (1) it provides for remote interrogation and possiblyeven automated monitoring of an animal's deep body temperature by meansof an indwelling probe implanted without surgery; (2) it providesinformation on ovulation on all animals, both those experiencing activeestrus and those who are not; and (3) it detects feverish conditions inadvance of clinical illness.

What is claimed is:
 1. The improved method for detecting a feverishcondition in mammalian females which comprises the steps of: attaching abattery powered radio telemetric temperature measuring device of a sizeadapted for insertion into the uterine canal to an expandable anchor ofapproximately the same size in collapsed condition as said telemetrydevice, collapsing the anchor and inserting it while thus collapsedalong with the telemetry device attached thereto the vagina to a depthwhere the assembly thus formed lies adjacent the cervix, expanding theanchor "in situ", monitoring the temperature daily from a remoteexternal location at approximately the same time each day for a periodnot less than approximately one complete estrous cycle, and comparingthe temperature each day with the average temperature over theimmediately preceding approximately ten day period to detect any abruptchanges therein of a magnitude several tenths of a °C. higher than thedeviation in temperature upon which said average temperature wasdetermined.
 2. The improved method as set forth in claim 1 wherein thetemperature is monitored for approximately 50 days.
 3. The improvedmethod as set forth in claim 1 wherein the daily temperature reading istaken between approximately 5:00 and 7:00 a.m.
 4. The improved method asset forth in claim 1 which includes the step of inseminating the subjectno later than one day following the day upon which said abrupttemperature change is detected.
 5. The improved method as set forth inclaim 1 which includes the step of treating the subject for febrileillness if said abrupt temperature change persists over one day. .Iadd.6. A method for detecting ovulation in a female herd animal selectedfrom the bovine, equine and porcine species and subject to climatictemperature variations, said method comprising the steps of:selecting anintravaginal anchor adapted for retention in said animals's vagina for aperiod not less than one complete estrous cycle of said animal andequipped with a telemetric temperature measuring device for relayingtemperature information from the animal to a location of a remotemonitoring station; inserting said anchor into the vagina of said herdanimal, maintaining said anchor in said vagina for a period of not lessthan one complete estrous cycle, and locating said animal in an areasuch that a range of said telemetric measuring device allows said deviceto relay said information to said station; measuring an intravaginaltemperature of said animal at least one time daily at approximately thesame time each day for a period not less than one complete estrous cycleof said animal; relaying said information to said remote monitoringstation; averaging temperature measurements taken over a plurality ofdays and comparing a temperature taken on a succeeding day with anaverage calculated in said averaging step; repeating said averaging andcomparing steps on each next succeeding day, the number of days of saidplurality of days remaining constant; identifying as a significantelevated temperature a temperature taken on one of said succeeding daysthat is at least several tenths of a degree Celsius higher than anaverage of temperatures for a preceding plurality of days and that alsoexceeds temperatures taken at approximately the same time on saidpreceding plurality of days; counting a number of days between saidsignificant elevated temperature and a previous temperature spikeattributable to a preceding onset of ovulation; and identifying saidsucceeding temperature as a subsequent onset of ovulation when saidcounted number of days is within about five days of an average estrouscycle length of said animal. .Iaddend. .Iadd.7. The method of claim 6wherein said period of not less than approximately one complete estrouscycle is approximately 50 days. .Iadd.8. The method of claim 6 whereinsaid same time is the period between about 5:00 and about 7:00 a.m..Iaddend.